rhist is extension of MATLAB hist function to compute and plot relative frequency and density.  
 
N = HIST(Y) bins the elements of Y into 10 equally spaced containers and returns the relative frequency of elements in each container. If Y is a  
matrix, RHIST works down the columns.  
 
N = RHIST(Y,M), where M is a scalar, uses M bins.  
 
N = RHIST(Y,X), where X is a vector, returns the relative freqency of Y among bins with centers specified by X. The first bin includes data between -inf and the first center and the last bin includes data between the last bin and inf.  
 
N = RHIST(Y,M,Any_Character) returns relative frequency density of Y among bins.Any_Character is the any character inside single quotation or any numeric value. You can omit second optional argument using single quotation i.e. N = RHIST(Y,'',Any_Character) returns relative frequency density for 10 bins.  
 
It is to be noted that sum(N)equals unity for relative frequency while area under curve for relative frequency density equals unity. Note that as size(Y,1) and M increases relative frequency density is close to probability density for continous random variable.  
 
[N,X] = RHIST(...) also returns the position of the bin centers in X.  
 
RHIST(...) without output arguments produces a histogram of relative frequency or relative frequency densisty.